Traditionally flat conveyor belts move product from point A to point B by carrying the product along a pre-defined route or track. Flat conveyor belt motion is driven by the contact between the belt and the drive pulley. The load on the belt is evenly distributed along the contact surface of the drive pulley.
Traditionally flat homogeneous belts are used in conveyor systems where cleanliness is of paramount importance. The term "homogeneous belt", as used herein, is an industry term that generally refers to an extruded belt or one made from a single material and is not reinforced. These belts provide a smooth continuous surface. Their non-absorbing surface allows for easy cleaning of spilled contaminants or remains from the manufacturing process. These belts are not likely to be carrying foreign materials which might contaminate the product being conveyed.
Belts of this type are driven by a pulley, generally at one end of the conveyor assembly. To ensure that the pulley has sufficient force to drive the belt, belts are pretensioned. Pretensioning is the placing of the belt under tension so that the friction between the belt and the drive pulley is sufficient to ensure that the belt does not slip against the surface of the pulley.
While pretensioning ensures that the pulley will drive the belt, there are resultant unavoidable issues. A properly pretensioned belt will slip against the surface of the pulley when lubricated with oils or other contaminants. Pretensioning by definition means stretching the belt. Homogeneous belts do stretch. Stretched belts require repretensioning at intervals determined by the stretching force applied to the belts. Belt stretching requires replacement after exceeding stretch limits.
Additionally, the load will also affect the stretch of the belt. Pretensioning also requires the additional cost associated with ensuring that the conveyor frame bed be sufficiently strong enough to withstand the stress placed on it. Further, improperly aligned belts will mis-track resulting in damaged belt edges and a shorter belt life.
Timing belts are used for accurate timed and indexed transmission of power from one drive wheel to another slave wheel. The drive wheel is notched with a pattern opposite to that of the timing belt. As the drive wheel rotates protrusions in the timing belt embed into depressions in the drive pulley forcing the belt to move.
Modular plastic chains and belting does meet the needs as far as positive driving and tracking are concerned, but they are a haven for dirt, product residue, bacteria, etc., and they are difficult, if not nearly impossible, to clean quickly or efficiently.
The present invention is directed to overcoming the above problems as well as other problems associated with the prior art conveyor belts.